Patent GB-600510-A (GB)
Title: Improvements in or relating to free-piston internal combustion engine gas producers or compressors
IPC: F02B71/00
Filed: 1945-03-09
Abstract: 600,510. Elastic-fluid turbines. SULZER FRERES SOC. ANON. March 9, 1945, No. 5898. Convention date, March 10, 1944. [Class 110 (iii)] [Also in Groups XXVII and XXVIII] A free piston engine compressor or gas generator has a device operated by the movement of one of the free pistons, which device controls a cut-out valve arranged between the generator or compressor and a service main and the stoppage of the piston automatically brings about closure of the cut-out valve. As shown, a gas generator 1 supplies combustion products through a pipe 10 and cut-out valve 12 to a service main 13 supplying a turbine 14. The cut-out valve 12 is operated by a stepped piston 16 which on one side is continuously loaded by a supply of a pressure medium at 18 tending to open the valve. The other side of the piston 16 is connected to atmosphere through pipes 26, 27 and 29 so long as a piston 30 remains in the position shown. The piston 30 is held in position by the pressure of a medium supplied from a small regulating pump 35 connected to one of the pistons 4 of the engine. If the engine stops, the supply of pressure medium from the regulating pump ceases and allows the piston 30 to rise to a position in which a supply of an independent pressure medium at 31 can flow to the underside of the stepped piston 16 and close the cutout valve 12. A simpler arrangement for operating the valve 12 can be employed in which pressure medium from the regulating pump can be supplied to the top of the piston 16 to hold it open against the action of a spring or the equivalent so that on stoppage of the pump the piston 16 is raised by the spring to close the valve. Closing of the valve 12 by hand can be effected by moving a cock 21 to a position in which pressure medium from the pipe 31 flows underneath a piston 24, raises it, and allows the pressure medium to flow through the pipe 25 to raise the piston 16 and close the valve. A piston 38 on the outlet side of the pump 35 is arranged to keep the pressure of fluid supplied constant by allowing it to escape whenever the pressure is above a certain value through the passage 39. The orifice 41 allows a continuous leak of fluid to atmosphere. In addition to the cut-out valve 12, a blow-off valve 15 is provided which is arranged and operated in the manner set out in Specification 600,509 referred to. The blow-off valve is loaded by a variable closing force which is normally maintained by a small amount above the opening force due to the pressure in a chamber 11. The closing force of the valve is produced by the. difference in load due to pressure medium supplied to a face 45 of a piston 44 connected to the valve and the load due to pressure medium supplied to a face 47 of the piston. The supply of pressure medium to the face 47 is controlled by two valves 49 and 58. The valve 49 is variably loaded by a cam 54 operated in dependence on the speed of the turbine. As the speed of the turbine increases so the load on the spring 50 is increased and the valve 49 is thus moved to the right. Thus, if the pressure in a pipe 56 is higher than that in a space 48 under the piston, pressure medium flows to the space 48. The pressure in the space 56 is controlled by the load on a spring 57 which is adjusted by a hand wheel 59. A non-return valve 62 is arranged between the compressor side of the engine which allows air to flow into the exhaust gas supply if the pressure of the air rises considerably above that of the exhaust gas. The arrangement of the cutout valves &c. described can be employed in a free-piston compressor as well as in a gas generator. The air supply to the compressors may be compressed in a rotary compressor driven by the gas generated by the plant or in the case of a free-piston compressor by a rotary compressor driven by the exhaust of the engine.